I would get it looked at. Lumps and bumps are serious when it comes to boxers who are known for cancers. With that said, that looks EXACTLY like the bumps that Riley got a LOT of. His always turned out to be histiocytomas which will usually go away on their own in a couple of weeks. Still, I'd want to get it looked to be 100% certain that's what it is. If you'd rather just try to wait it out, I'd give it a week or so to see if it changes in size or shape. If it starts going away it should be nothing to worry about, but if it gets bigger or the texture changes definitely have it checked out,

It looks like a histiocytoma to me. I personally wouldnt run back to vet just quite yet. You have a long road ahead of you with healing from surgery. Give him a couple of weeks and see if the swelling goes down.

Lots of kisses for Lukin. Poor guy has had a rough go, hopefully its only uphill from here.

__________________Kari ~ Keeper, servant and mommy to the following crew